Light rail systems attract cute names. TriMet’s original light rail, running from downtown Portland to central Gresham, was given the name MAX, short for Metropolitan Area eXpress. (The name stuck, even though it served only a small portion of the metropolitan area, wasn’t very fast, and would actually be MAE instead of MAX.) No such cute name was found ten years later for the west side extension to Hillsboro, which was called simply West Side Light Rail. (I proposed returning to acronymic accuracy and calling it MAE West, but TriMet doesn’t share my sense of humor.)
The light rail that’s soon to open on the transit mall (Fifth and Sixth Avenues), will need a nickname. The southbound line will run past the Multnomah County Courthouse. I suggest referring to riding that line as "taking the Fifth."